Unsaturated polyesters and the terminally unsaturated vinyl ester resins resulting from the esterification of unsaturated monocarboxylic acids and polyepoxides have found widespread utility in diverse applications, such as coatings, laminates, moldings and the like. Such resins are known to be polymerizable by exposure to ultraviolet light.
The viscosity of such resins is usually so great as to make fabrication by the usual techniques extremely difficult and impractical. It is commonplace to reduce the viscosity by blending the resin with a relatively low molecular weight monounsaturated reactive diluent, such as styrene or the alkylacrylates, which react with the unsaturation of the resin. In so doing the degree of functionality of the resin system is lowered with a consequent alteration of the properties. Also such reactive diluents are frequently volatile or toxic materials.
It would be desirable to have such a polyester or vinyl ester resin system which would have a high cross-link density without requiring excessive amounts of volatile diluents.